PICO-8 Demo of a ball moving with arrow keys

demo.p8

pico-8 cartridge // http://www.pico-8.com
version 16
__lua__
-- move an ball on-screen
-- by erik hollembeak

SCREEN_WIDTH = 128
SCREEN_HEIGHT = 128

-- Ball definition
Ball = {
  x = 64,
  y = 64,
  sprite = 0,
  speed = 3
}

-- screen is a manifold that wraps at edges
function _update()
  if btn(0) then
    Ball.x = (Ball.x - Ball.speed) % SCREEN_WIDTH
   end
   if btn(1) then 
     Ball.x = (Ball.x + Ball.speed) % SCREEN_WIDTH
   end
   if btn(2) then 
     Ball.y = (Ball.y - Ball.speed) % SCREEN_HEIGHT
   end
   if btn(3) then 
     Ball.y = (Ball.y + Ball.speed) % SCREEN_HEIGHT
   end
end

function _draw()
 cls()
 rectfill(0, 0, 127, 127, 1)
 spr(Ball.sprite, Ball.x, Ball.y)
end